Applies To:

BIG-IP WOM

What is symmetric data deduplication?

WAN Optimization Manager (WOM) uses symmetric data
deduplication to reduce the amount of bandwidth consumed across a WAN link
for repeated data transfers. This feature is available only with a WOM® license.

With data deduplication, the system performs pattern matching on the transmitted WAN
data, rather than caching. If any part of the transmitted data has already been sent,
BIG-IP® WOM replaces the previously transmitted data with
references. As data flows through the pair, each WOM records the byte patterns and
builds a synchronized dictionary. If an identical pattern of bytes traverses the WAN
more than once, the BIG-IP WOM closest to the sender replaces the byte pattern with a
reference to it, compressing the data. When the reference reaches the other side of the
WAN, the remote BIG-IP WOM replaces the reference with the data, restoring the data to
its original format.

Which codec do I choose?

Symmetric data deduplication (SDD) offers two versions, called codecs. SDD v3 is
appropriate for most WOM installations, particularly in large networks,
such as hub and spoke, or mesh deployments. SSD v2 is an alternative for
installations with fewer than eight high-speed links, such as for data replication between data
centers.

For deduplication to occur, the same codec must be selected on both iSession endpoints. If
the selected codecs do not match, deduplication does not occur, although other WOM features,
such as compression, still take place.

Enabling symmetric data deduplication

Ensure that you have licensed and provisioned WAN Optimization
Manager™ (WOM) on the BIG-IP® system.

Symmetric data deduplication (SDD) reduces the amount of bandwidth consumed
across a WAN link. You can enable symmetric data deduplication on the iSession™ connection between the local endpoint and any remote endpoints. SDD
is enabled by default when you provision WOM®.

On the Main tab, expand WAN Optimization and click
Symmetric Deduplication.

In the Maximum Number of Remote Endpoints field, type
the number of BIG-IP WOM systems that you expect to connect to this one.
This number specifies the maximum number of remote endpoints that can have
symmetric data deduplication enabled, and thus, share the available cache. Any
added WOM remote endpoint that exceeds this number receives no cache for
deduplication. If you select SSD v2 in the
Codec field, the maximum supported is
8. If you select SSD v3, the
set value is 128.

For the Enable Symmetric Deduplication setting, select
Yes.

For the Mode setting, select the method of storage for
symmetric data deduplication.

Option

Description

Disk

Specifies that WOM uses the disk, in addition to memory, for storing
information used for optimization.

Note: If you enable data
storage on the disk, you must restart the datastor service from the
command line using the command sequence bigstart restart
datastor for the change to take effect.

Memory

Specifies that WOM uses only memory for storing information used for
optimization.

Note: This setting can provide benefits for
higher speed links.

For the Codec setting, select the SDD version.

Option

Description

SDD v3

Supports a high spoke count, such as for connecting remote sites and
for mesh topologies.

SSD v2

Supports a topology with fewer than eight spokes, such as
replicating data between data centers.

For SDD to occur between iSession endpoints, you must select the same codec on
both the local and remote BIG-IP WOM systems.

Click Update to save changes.

Important: Updating any of these settings causes the deduplication
cache to clear.

Symmetric data deduplication starts after an iSession connection is established with
a remote endpoint that also has symmetric data deduplication enabled, provided that the
number of remote endpoints does not exceed the value in the Maximum Number of
Remote Endpoints field.

If you changed the Codec setting, the system applies the new
setting to any new data flows. However, if you enabled or disabled SDD, you must then
restart the BIG-IP WOM from the command line using the command sequence bigstart
restart.

Disabling symmetric data deduplication

You can disable symmetric data deduplication on the iSession™
connections between the local endpoint and any remote endpoints.

On the Main tab, expand WAN Optimization and click
Symmetric Deduplication.

For the Enable Symmetric Deduplication setting, select
No.

Click Update to save the change.

Restart the BIG-IP WOM from the command line by typing bigstart
restart.

Symmetric data deduplication stops on all iSession connections between the local
endpoint and any remote endpoints, and the deduplication cache clears.